This invention relates to an improvement in machines, commonly referred to as bundle breakers or bundle separators, which separate a plurality of stacked sheets, hereafter a bundle, from a plurality of stacked sheets, hereafter referred to as a log. Each sheet is divided by one or more weakened lines and each log is divided by one or more weakened planes. Bundle breakers in the corrugated board industry are typically located in a production line between a sheet stacker on the upstream side and a load former which arranges the bundles in pallet loads on the downstream side.
A wide variety of products are manufactured in elongated sheets and divided into smaller segments as by scoring, indenting, nicking, tabbing or punching; creating weakened planes in the material. Such products include composition house roofing shingles, glass plates, paper, plastic, and corrugated board used in constructing boxes and packaging material
Early machines in the above designated categories, separated small segments from a larger sheet. Examples include: Olsen U.S. Pat. No. 1,669,999, 1928 for composition shingle; Stolar, U.S. Pat. No. 1,171,769, 1939, paper sheet; Zellers, U.S. Pat. No. 3,286,89, glass sheet; Dryon, U.S. Pat. No. 3,517,869, 1970, glass sheet using tilting table; Norton, U.S. Pat. No. 3,658,220, 1972, cardboard sheet; Barozzi, U.S. Pat. No. 5,069,195 1991; and Vossen, U.S. Pat. No. 4,171,081, 1979, cardboard sheet.
As the speed of machines creating long strips of sheet material increased and the advantages of arranging the sheet material into stacks became apparent, machines were developed for separating a plurality of sheets or a bundle from the stack of sheets or log. Each log was separated into a plurality of bundles. Separation, was effected by aligning the weakened planes of each sheet into a single vertical plane. The first machines, such as Schmidt, U.S. Pat. No. 4,136,604, 1979 applied clamps on either side of the weakened plane and effected separation of the bundles from the log by applying force downwardly on the bundle side of the weakened plane. This method required tremendous punching force since all of the sheets were essentially separated at the same time. The use of high force as used by Schmidt compressed and often damaged the cardboard sheets in the separation process.
Lucas, U.S. Pat. No. 4,500,022, 1985 introduced progressive tearing force along the weakened plane thereby reducing the punching force of Schmidt and reducing damage to the cardboard.
Fernandez, U.S. Pat. No. 5,865,358, 1999 introduced progressive tearing in a cardboard bundle by maintaining the bundle and log in a horizontal plane and pivoting the bundle about a vertical axis away from the log.
Vanhoutte, of Brugge Belgium, European patent 292 067, 1994, application published 1988, patented a cardboard bundle breaker which progressively severed the cardboard bundle from the log by pivoting the bundle portion downward about a horizontal pivot axis.
Pallmac , of Brugge, Belgian, installed a bundle breaker of cardboard sheets in Sanger, Calif. USA in 1994. The Pallmac machine progressively severed the cardboard bundle from the log by pivoting the bundle portion downward about a horizontal pivot axis.
Duecker, U.S. Pat. No. 5,927,582 was granted U.S. Pat. No. 5,927,582 in 1999 on a patent application filed Aug. 5, 1997 which did not cite the Pallmac bundle breaker, supra or the Vanhoutte bundle breaker supra. Duecker progressively severed the cardboard bundle from the log by pivoting the bundle portion upward about a horizontal pivot axis.
Shill, U.S. Pat. No. 6,019,267, in 2000 progressively separated a bundle from a log by progressively tearing the bundle starting at a point and pivoting the bundle along an X and a Y plane. By progressively simultaneously tearing along two planes, the clamping force required to hold the cardboard bundles was further reduced.
In order to speed production, Pallmac, 1994, e.g. feeds two or more logs through its bundle breaker and severs a plurality of bundles simultaneously from the side by side logs. One of the problems associated with breaking multiple bundles from multiple logs is that one or more logs may be higher than the others due to a miscount in the number of sheets or the accidental insertion of scrap pieces of material between one or more sheets of the log. It is sometimes possible that where there are three or more logs, all may have different heights.
When both top and bottom surfaces of the clamps are rigid, more pressure is exerted on the taller logs which can damage compressible material like corrugated cardboard. If the logs are not compressible, then insufficient pressure is placed on the shorter logs and shifting of the logs can occur when the bundles are broken off from the log either by pivoting the bundle about a horizontal or vertical axis or a combination of both. In the industry, this problem is called a xe2x80x9clack of compliancexe2x80x9d problem; i.e. the force on all the side by side logs is not substantially equal.
To solve the lack of compliance problem some companies have inserted spring material such as foam between the face of the rigid clamp and the logs. Springs and foam rubber do not distribute the clamp force evenly between side by side logs. Springs and foam materials increase pressure with displacement.
Pallmac sought to solve the compliance problem by placing a small diameter elongated air bag below the rigid lifting members near the break line of the bundle breaker and at right angles to the direction of flow of the material.
Pallmac uses a plurality of narrow spaced apart conveyor belts and lifting members which are located between each belt. The Pallmac air bag is part of the lifting mechanism. Before a bundle can be broken from a log, the lifting mechanism must lift the log up into engagement with the upper hard vertically adjustable fixed clamp. Since the length of the log often exceeds the length of the lifting members, the portion of the log hanging off the end of the lifting members will no longer be horizontal. As the lifting members lower the log, a shifting of the individual sheets within the log can occur which changes the position of the weakened plane and can result in failure to break the bundle cleanly from the log or produce poorly formed bundles. As the variation in the logs increase, the upper hard vertically adjustable clamp needs to be adjusted upward, which increases the shifting effect of the individual sheets.
Siebels, provided vibration damping in a vibratory table for separating sheets of glass which have become stuck to one another in an annealing process by providing an air bag 62 (see FIG. 3). This use of an air bag has no relevance in solving the compliance problem when logs of uneven height are to be broken.
The essence of the invention is the provision of a fluid pressure compliance structure to provide reliable breaking of multiple side-by side bundles from multiple side by side logs by applying equal pressure to all of the logs and severed bundles.
Wherever the words xe2x80x9cfluid pressurexe2x80x9d are used in this application, the word xe2x80x9cfluidxe2x80x9d includes liquid as well as gas. Liquids may include water or other fluids. The word xe2x80x9cgasxe2x80x9d includes air as well as other gases. Applicants found that air is the preferred fluid for applications in the corrugated board industry.
It is an object of the present invention to provide a compliance structure which can be used in breaking bundles from logs which are composed of sheets of corrugated board.
It is a further object to provide a device which can also be used in breaking sheets of different materials arranged in logs such as glass, roof shingle materials made from various composition materials, sheets of plastic arranged in logs, and other sheet material formed in stacks in which the logs contain one or more weakened planes.
It is a further object of the present invention that the compliance structure having a fluid inflated structure be used in bundle breakers in which the downstream clamp member pivots about a horizontal axis and the bundle is pivoted upwardly as in the Duecker U.S. Pat. No. 5,927,592 patent.
It is a further object of the present invention that the compliance structure have a fluid inflated structure and in which the downstream clamp pivots about a vertical axis as shown in the Fernandez U.S. Pat. No. 5,865,358 patent.
It is still another object of the present invention that the compliance structure have a fluid inflated structure and in which the downstream clamp pivots about an X-Y axis as shown in the Shill U.S. Pat. No. 6,019,267 patent.
A major feature of the present invention is a structure which can easily detect and transmit the information that the first compliance structure has touched the highest log adjacent the bundle breaking plane.